arm64/perf: Replace PMU version number '0' with ID_AA64DFR0_EL1_PMUVer_NI

__armv8pmu_probe_pmu() returns if detected PMU is either not implemented or
implementation defined. Extracted ID_AA64DFR0_EL1_PMUVer value, when PMU is
not implemented is '0' which can be replaced with ID_AA64DFR0_EL1_PMUVer_NI
defined as '0b0000'.

Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Anshuman Khandual <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Anshuman Khandual

arch/arm64/kernel/perf_event.c

@@ -1146,7 +1146,8 @@ static void __armv8pmu_probe_pmu(void *info)
 	dfr0 = read_sysreg(id_aa64dfr0_el1);
 	pmuver = cpuid_feature_extract_unsigned_field(dfr0,
 			ID_AA64DFR0_EL1_PMUVer_SHIFT);
-	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF || pmuver == 0)
+	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF ||
+	    pmuver == ID_AA64DFR0_EL1_PMUVer_NI)
 		return;
 
 	cpu_pmu->pmuver = pmuver;